Basically, a formula that works out how many squares a grid of any given size contains. EG: 8*8 grid has 204 possible squares within it (1², 2², 3², 4², 5², 6², 7², 8²)

Is this any clearer?

It was clear the first time for the sum.It is after all a sum and not a product.
I gave you the formula for the sum.
This is a well known problem and you have been given the solution twice on this board.